Technological Field
The present invention relates to a colorimetric chart creating apparatus that creates a colorimetric chart that expresses desired information by an arrangement order of patches, and a colorimetric chart method, and a program.
Description of the Related Art
When a printing device performs a print output, deviation (color deviation) in color reproducibility is caused in a printed matter due to various causes such as device characteristics and change over time even if the printing device outputs a desired color on data.
Therefore, printing a colorimetric chart at appropriate timing and confirming whether the color deviation falls within an allowable range, or printing the colorimetric chart, calculating correction data for causing a color of an image formed on a sheet of paper to fall within an allowable range from a measurement result of a color obtained by reading the colorimetric chart with a colorimeter, and correcting an image signal value using the correction data, in order to correct the color deviation, are performed.
By the way, when there is a plurality of printing devices, colorimetry needs to be performed under correct recognition of which printing device the colorimetric chart has been output from. However, since the colorimetric charts output from the respective printing devices have the same pattern, visually identifying the colorimetric charts is difficult and a user may get a wrong colorimetric chart to be checked. Further, there is a problem that, in a case where an old colorimetric chart is read with the colorimeter, the current printing device may erroneously grasp the color reproducibility.
Typically, as a countermeasure to the above problem, directly printing information of the printing device that has printed the colorimetric chart, print date and time, and the like on a margin of the sheet of paper on which the colorimetric chart has been printed, or printing a barcode indicating the information is conceivable.
However, considering a possibility that the user may misread letters in the case of printing letters and a fact that a special reader is separately required in the case of a barcode, it is desirable to determine the information indicating the printing device that has printed the colorimetric chart as an object to be read, the print date and time, and the like, from read data of the colorimeter.
For example, JP 2016-158136 A discloses a method of expressing information of a printing device, print date of time, and the like by an arrangement order of patches constituting a colorimetric chart, and acquiring the information from a colorimetric value read with a colorimeter.
In the method disclosed in JP 2016-158136 A, the arrangement order of the patches to be arrayed in the colorimetric chart is changed according to information to be embedded. Therefore, a patch in which color is arrayed in each place is determined from the colorimetric value read and obtained by the colorimeter. However, if a plurality of patches in close colors in which error ranges of color reproducibility overlap with each other is used, misrecognition of a patch occurs due to color deviation in a case of reading the patches with the colorimeter, and the information of the printing device, print date and time, and the like may not be able to be correctly read. Specific examples will be described below.
FIG. 25 illustrates an example of expressing information of a printing device, print date and time, and the like by the method disclosed in JP 2016-158136 A. In FIG. 25, the printing device and the print date and time are expressed by the arrangement order of patches of eight different colors A to I. The arrangement order of the three patches from the left expresses an identifier of the printing device, and the arrangement order of the fourth and subsequent patches expresses the print date and time.
In FIG. 25, there are patterns of the arrangement order of (ABCDEFGHI) and (ACBDEFGHI), the case of the left three patches ABC indicates that the printing has been performed by a device 1, and the case of the left three patches ACB indicates that the printing has been performed by a device 2. Furthermore, the order of patches DEFGHI from the fourth patch from the left to the right end patch indicates that the printing date and time is at 14:40 on Dec. 20, 2015.
FIG. 26 is a diagram illustrating distribution of the colors indicated by the patches A to I in FIG. 25 on an Lab color space 100 in a simplified manner. In FIG. 26, the center of a circle surrounding an alphabet representing each patch indicates coordinates indicating an original color intended to be printed with the patch. The range of the circle is a color range (hereinafter referred to as error range) that can be taken by the colorimetric value when printing is performed and a print result of the printing is colorimetrically measured.
In FIGS. 26, B and C partially overlap with each other in the error ranges. Therefore, in a case where the color indicated by the colorimetric value obtained through the colorimetry is a color falling within the overlapping range, the colorimeter may misrecognize which of the B and C patches has been printed.
For example, in FIG. 26, coordinates B1 located in an end of the error range of B and in a position overlapping with the error range of C is closer to the B coordinates (the center of the circle of B) than to the coordinates C (the center of the circle of C). Therefore, in a case where B1 appears as a print result at the time of printing B, B1 may be misrecognized as the patch C at the time of colorimetry. Further, coordinates C1 located in an end of the error range of C and in a position overlapping with the error range of B is closer to the C coordinates than to the coordinates B. Therefore, in a case where C1 appears as a print result at the time of printing C, C1 may be misrecognized as the patch B at the time of colorimetry.
FIG. 27 illustrates arrangement of patches and Lab values of the patches on data at the time of printing, and arrangement of the patches and Lab values of the patches recognized from a colorimetry result.
On the data, the patches of the colorimetric chart are in the arrangement order of ABCDEFGHI, and indicate that printing has been performed by the device 1 at 14:40 on Dec. 20, 2015, similarly to FIG. 25.
However, the order of the patches recognized from the colorimetry result obtained by colorimetrically measuring the print result is an arrangement order of ACBDEFGHI, and the patch B in which the color deviation has occurred is misrecognized as the patch C, and the patch C in which the color deviation has occurred is misrecognized as the patch B. Due to the misrecognition of the arrangement of the patches, it is misrecognized that the printing has been performed by the device 2 at 14:40 on Dec. 20, 2015.
Therefore, measures to prevent misrecognition due to such color deviation are desired.